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epithelial tissue
- occurs as sheets of cells
- cover the outside of the body; lines organs and cavities within the bodies
- functions as a barrier against mechanical injury, pathogens, fluid loss
- polar (2 sides)
- form active interfaces with the environment
- cuboidal, simple squamous, stratified squamous, simple columnar, pseudostratified columnar
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polar epithelial cells
- 2 sides are apical surface and basal surfaceapical surface faces the lumen and may have specialized projections
- basal surface is attached to the basal lamina, which separates the epithelium from the underlying tissue
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cuboidal
- specialized for secretion
- kidney tubules and glands (thyroid, salivary)
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simple squamous
- single layer of cells
- thin and leaky
- functions in exchange of material by diffusion
- lines blood vessels and the air sacs of lungs
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simple columnar
- found where secretion or active absorption is important
- lines the intestines
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pseudostratified columnar
- single layer of cells varying in height
- ciliated cells form a mucous membrane that lines portions of the respiratory tract
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stratified squamous
- multilayered and regenerated rapidly
- found on surfaces subject to abrasion
- outer skin and linings of the mouth, anus, vagina
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connective tissue
- sparse population of cells scattered through an extracellular matrix
- holds many tissues and organs together and in place
- consists of a web of fibers embedded in a liquid, jellylike, or solid foundation
- collagenous, reticular, elastic fibers
- loose and fibrous connective, cartilage, bone, blood, adipose
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collagenous fibers
provide strength and flexibility
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reticular fibers
join connective tissue to adjacent tissues
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elastic fibers
makes tissues elastic
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loose connective tissue
- binds epithelia to underlying tissue and holds organs in place
- includes all three fibers
- found in skin and throughout body
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fibrous connective tissue
- dense with collagenous fibers
- found in tendons and ligaments
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bone
- ossified
- osteoblasts (deposit a matrix of collagen)
- repeating units called osteons
- mineralized by phosphate, magnesium, calcium ions
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blood
- liquid exterior matrix called plasma
- erythrocytes (RBC)
- leukocytes (WBC)
- platelets
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adipose tissue
- specialized loose connective tissue that stores fat in adipose cells distributed throughout the matrix
- pads an insulates
- stores fuel as fat molecules
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cartilage
- collagenous fibers embedded in a rubbery protein-carbohydrate matrix called chondroitin sulfate
- chondrocytes secrete collagen and chondroitin sulfate
- replaced by bone as the embryo matures
- disks act as cushions between vertebrae
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muscle tissue
- responsible for nearly all types of muscle movement
- consists of actin and myosin filaments, contraction proteins
- skeletal, smooth, cardiac
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skeletal muscle
- attached to bones by tendons
- striated
- responsible for voluntary movements
- consists of muscle fibers and sarcomeres (contractile elements)
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smooth muscle
- unstriated
- responsible for involuntary bodily movements
- cells are spindle-shaped
- found in walls of digestive tract, urinary bladder, arteries, other internal organs
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cardiac muscle
- striated
- forms contractile walls of the heart
- has fibers that interconnect via intercalated disks, which relay signals
- help synchronize heart contraction
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nervous tissue
- neurons and glia
- a concentration of nervous tissue forms a brain
- functions in the receit, processing, and transmission of information
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nerve cells (neurons - brain)
- receive nerve impulses via dendrites
- relay nerve impulses via axon
- unidirectional
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glial cells
- various types
- support cells
- nourish, insulate, replenish neurons
- modulate neuron function
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